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Matthew Sturm
Matthew Sturm 2003

Matthew Sturm gave a powerpoint presentation about snow, ice and climate change at the annual meeting of OLCG teachers on December 6-7, 2003 at the University of Alaska Fairbanks in Fairbanks, Alaska. The theme of the meeting was snow and ice. In this presentation, Matt talks about the science of snow and the effects of climate change in Alaska.

Digital Asset Information

Archive #: Oral History 2001-113-10

Project: Climate Change
Date of Interview: Dec 6, 2003
Narrator(s): Matthew Sturm
Location of Interview:
Funding Partners:
National Aeronautics and Space Administration (NASA), National Science Foundation
Alternate Transcripts
There is no alternate transcript for this interview.

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Begin Slide Show. Click here for first image.  Click here for second image.

Pictures of snow crystals and layers of snow. Click here for first image.  Click here for second image.

Layers of snow and types of snow. Click here for first image.  Click here for second image.

Metamorphic changes graph. Click here for image.

Trapped snowflake experiment. Click here for image.

Snow changes into two pathways. Click here for image.

Snow crystals. Click here for first image.  Click here for second image.  Click here for third image.  Click here for fourth image.

Bonds of snow crystals. Click here for image.

Properties of a snow pack. Click here for first image.  Click here for second image.

Thermal conductivity. Click here for image.

Thermal conductivity data collection. Click here for image.

Pathway of a layer cake. Click here for image.

Alaska climate changes. Click here for image.

Landscape changes. Click here for first image.  Click here for second image.

Soil pit. Click here for image.

Graph: effects of warming. Click here for image.

Albedo and solar radiation. Click here for first image. Click here for second image.

Graph: measuring albedo throughout a melt season. Click here for image.

Monthly snow cover charts. Click here for first image.  Click here for second image.  Click here for third image.

Feedback loop. Click here for image.

Sea ice is shrinking. Click here for image.

Water resources. Click here for image.

Final thoughts. Click here for image.

Begin question and answer portion.

Looking at snow crystals in the classroom.

Information on slides.

Snow-up and break-up.

How climate effects people's lives.

Explanation of albedo.

Climate change.

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After clicking play, click a section of the transcript to navigate the audio or video clip.


Elana Sparrow: I have the pleasure of introducing Dr. Matthew Sturm. He has -- he has been working on -- for 20 years on snow, and he really loves his work. And also has been working with teachers and students and has also enjoyed doing that. He works for the Corps of Engineers in the Cold Regions Research and Engineering Laboratory. He is -- he got his Ph.D. from the University of Alaska Fairbanks and he is one of our UAF stars. He is well known internationally -- nationally and internationally for his work on snow. And so we have the privilege of listening to him about -- talk about his work. Matthew: Thank you. I’m kind of wired here. This is pretty good. Have you got an EKG? I wanted to wear my kid’s shirt. I spend a lot of time with kids, and so that’s kind of why I’m here more than about snow. Because I think if you live in Alaska and you’re teaching kids, you’ve got one of the best natural laboratories out there possible. And it’s -- it’s easy to get kids excited about snow science. But I got asked today not really to talk about the experiments, I think you get that later today and tomorrow, but to put this in a bigger context of really what’s one of the major scientific issues perhaps of our lifetimes or many lifetimes, which is climate change. So if someone would want to turn the lights down a little bit, let’s kind of get the lights down here and see if all our technology will work, you know. Too much? MEMBER OF AUDIENCE : (Inaudible.) Matthew: Well, I’ve got to get the computer back out of sleep mode. Here we go. This is always a problem with too much technology. Hang on. Oh, look at that. There we go. Okay. MEMBER OF AUDIENCE : Do you wanted this dark? You wanted this dark? Matthew: Yeah, I think that will work fine. And I’m going to stand here. I tend to jump around, but... So what I want to talk to you about today is put the snow and measurements of snow in the context of climate. I’m starting from the point here, and I don’t -- I’m not really going to go through it, the climate is changing. You may read in the paper that there are a few people who don’t think so, but I’d say 99 percent of the scientists working on climate change, and particularly in the Arctic, are convinced we are entering an era of quite different conditions. So this talk really starts from the point that the climate’s changing. And you can ask questions later if you want me to get into that, but more I want to show you why snow is such an important part of climate change if you’re dealing with -- if you’re working in Alaska. So that’s really what it’s about. And we’ll come back to climate change, the evidence for it, if you want, later, but just that’s sort of my starting point, now, why snow -- snow’s so important.

Click here for image.  Snow crystals are hexagonal. Tetrahedral is the building block of snow.Magonal and Lee International Classification of Hydro-meteorites diagram. Matthew: And I wanted to start right from the beginning. Okay. The water molecule. We’re going to get to climate, but Blake once said you could see the world in a grain of sand. And if you want to understand how snow, this white stuff, fits into climate, you’ve got to start right down here. And I kind of colored in the red for the oxygen molecules and the yellow for hydrogen clouds. I don’t actually want to do the physics, but start from the little building block, the little tetrahedron, see it there, kind of a tetrahedron. And if you start tinker toys of tetrahedron, tetrahedron, you put them together, you get a hexagon. Squint and look at now outside of my one picture and you can see little hexagons. That’s where the symmetry of snow comes from. That’s where snow crystals come from. Right from the molecular structure. It’s manifested all the way up through snowflakes and so on. So that little molecular tetrahedron produces an incredible array of forms that fall out of our sky. One of the most magical things that happens is that nature gives us -- this is a list from Magonal and Lee, from the International Classification of Hydro meteorites, fancy name for snowflakes. Well, some aren’t -- we need that word because some aren’t snowflakes. On the right lower corner we have graupel, hail. Just lots of things that fall from the sky that are aren’t liquid. They are called hydro meteorites. But hexagons all through there because of that little tetrahedron. So that’s the building block of snow. Kids should know that.

Pictures of snow crystals found on the web:Click here for image. Dr. Matthew Sturm's diagram showing snow layers over a winter: Click here for image. Matthew: And, of course, it produces this wonderful set of forms -- oops, I’ve got to go back here. And almost all these are available on the web. If you haven’t found these websites, talk to me. There are -- there’s a Caltech website that has the most beautiful snow crystals on it. Bentley crystals are available without copyright, Snowflake Bentley. On the middle picture, SEM, there’s a -- in Rockville, Maryland, the Department of Agriculture scanning electron microscopy site. There’s no reason kids anywhere in Alaska with access to a computer can’t see the most beautiful snow crystals, even if you can’t cast them yourself. Hexagons, all, from that tetrahedron. But when we’re going to get to climate, it’s not just the hexagon, it’s also that we build up a layered structure. A series of weather events -- clear days, cloudy days, snow -- fill this nice layer cake, and that’s the primary element that a snowpack imply -- imparts to climate, the layers. And this is a standard pit diagram. This is one of mine from when I was up at SHEBA, up north of Alaska on the sea ice, but just a nice little figure to show that layer cake structure. The symbols tell you what type of snow it is. We’ll talk about that in a second. But the little -- the little building blocks then build bigger layers, which are layers, the layers stack up, and the way they stack up and the nature of that, that’s what imparts the importance of snow to climate.

Dan Solie measuring snow in Fairbanks: Click here for image. Perennial snow persists year round, like on a glacier and seasonal snow melts every summer: Click here for image. So all of those combined produce what’s on the ground, which is really where the impact comes from. And here is my friend Dan Solie, he’s looking at the snow right here in Fairbanks a few years ago, and you can see the layers and its interactions. Okay. There are actually -- I think probably no one here is going to deal with perennial snow, but snow can fall out here in a taiga, in a tundra, or it can fall on a glacier. And there’s actually some slight differences. So we tend to look at -- we tend to think there’s two types of snowpacks: Perennial snowpacks, those that don’t go away in the summer; and seasonal snowpacks, which is what most of you are probably dealing with with your kids, right? Comes, falls, builds up, melts in the spring, and it’s gone. There’s a lot in common between those two because the layer -- the layer keeps -- the layers build up, the layer cake builds up and everything. The difference is in the perennial snow, if you dig down deep enough, you’re going to find last year’s snow; whereas in your snow, you dig down deep enough, and hopefully you’ll find tundra, the street, or a parking lot. Okay. But that difference does exist out there. And actually, when I get to albedo, I’ll show you why it might be important.

Click here for image. This is another key point. Snow never exists more than 70 degrees from its melting point. The coldest I’ve ever seen it is like minus 70, and that’s only 70 de -- no, that’s not 70 F, so it would probably be minus 50 C maximum. That’s -- that’s not very far from its melting point. This building, the steel in this building is a thousand degrees from its melting point. Any material that’s held very close to its melting point has pretty weird properties, so one of the things you want to stress and that plays a big role in how snow functions is the fact that it’s right near its melting point. Because sometimes it’s just a degree or two from its melting point. A steel building that was 3 degrees from its melting point would just ooze down into the street and fall apart. All right. The World Trade Center showed us what happens when metal gets close to its melting point or at it. The snow’s always that close, so keep that in mind. That’s why it does some strange things. The second thing is high vapor pressure. What’s a high vapor pressure material? Well, gasoline, we’re used to that. If you can smell it, it must have a high vapor pressure. We don’t tend to think of water and ice having a high vapor pressure, but hang a pair of clothes -- pants on a line, they will freeze and then they’ll dry, right? It’s because it has a high vapor pressure. Both these things mean that snow, once it hits the ground, isn’t very stable. It’s not a stable substance. So it changes. That’s called metamorphism, and we see it all the time, but this is why. It’s close to its melting temperature, has a high vapor pressure. It’s going to change. How does it -- so this curve here, by the way, is the vapor pressure curve. It’s not really important other than to notice what comes up when it gets close to zero. So the closer we get to zero, the more unstable. And that’s what it does.

Experiment: A trapped and isolated snowflake was kept at a constant temperature and it still changed over 67 days. Snow is not stable.Click here for image. This is a cool experiment that was done about 60 years ago. They found they had a snowflake and they trapped it on a glass slide, they isolated it, and they kept it at perfectly the same temperature, so they didn’t melt it or anything, they just wanted to see if it was stable. Does it look stable to you? It’s 67 days after they trapped it, without ever melting it, it rounded off. Why? It’s near its melting point and it has a high vapor pressure. The little water molecules, those little tetrahedron, they just -- they hate to be a point. They don’t want to be a point or anything, they want to be a nice round curve. So they come off of the points and they go into the curves. So this is the type of processes that happen once that hydrometeorite falls out of the sky and lands down here on the snowpack, it’s going to start doing this. So the snow’s going to change. Why is that important to climate? We’ll get to that in a second, but it does matter.

Snow changes when it lands on the ground into two different pathways. Click here for image. So what we get is that snow that falls on the ground will change, and it tends to follow one of two large pathways. The equilibrium pathway, if you’re familiar with old avalanche literature, it’s called ET, that’s the pathway whereby it turns round. That’s a pathway in which the temperatures and the temperature gradients are pretty minor. The other pathway is called kinetic growth and it’s going to get sharp edges. And those two are going to give us real different properties for snow. You’re going to see that everyone in Alaska that takes their kids out to look at snow can see both of these. They are both out there. Typically kinetic, or TG or depth hoar, right now in Fairbanks, and I would suspect Nome and wherever you guys are from, you have a relatively thin snow still, and if you dig down to the bottom, there’s going to be some kinetic growth already. MEMBER OF AUDIENCE : So what determines which pathway it goes? Is it temperature or -- Matthew: The temperature gradient. MEMBER OF AUDIENCE : Temperature. Okay. Matthew: The temperature gradient, not the temperature. If there’s a strong warm at the bottom and cold at the top, she’ll go down the kinetic pathway. If it’s warm at the bottom and warm at the top, it will -- it will tend to round. If it’s cold at the bottom and cold at the top, it will tend to round. So it’s only if there’s a strong gradient across it, it will go down the kinetic pathway. It doesn’t matter for climate. Well, let’s look at what they look like.

Melt grain clusters. Click here for first image.  Click here for second image.  Click here for third image.  Click here for fourth image. This is the real round end, right? So warm it’s going to melt. Look at those. Aren’t those beautiful crystals? Yeah, they are. They are cool. Nature did this, made these beautiful balls. Notice the little kind of connection -- I’m so wired I can’t -- I can’t touch it. I don’t know if there’s a cord, but see little places they touch. Just put that in your mind for a second. That’s okay. I mean, I think I’m okay. And we can move to something kind of intermediate, wind grains. Snow grains that have been tumbled across the ground, they kind of got fractured like you hit glass spheres with a hammer, and then again, then they glue together. Move into the kinetic growth, I color coded these to the red ones. Look, we start to get beautiful shapely facets. You know, a little different than those rounded ones. And finally, this is what we’ll find near the ground, particularly if you go on a lake surface, really skeletal striated growth, the ultimate in kinetic growth forms. So this had a really strong temperature gradient making it, the rounded ones had almost no temperature gradient. Okay. So far, so good. MEMBER OF AUDIENCE : Can I ask a question? Matthew: Sure. MEMBER OF AUDIENCE : How much is no -- I mean, what constitutes a big temperature gradient? Matthew: You need about 25 degrees per meter to drive kinetic growth. Somewhere between 10 and 25. So a sort of rule of thumb is if you have a half meter of snow, right, and you’ve got a drop of, say, 15 degrees across it, you’ll get kinetic growth. It’s just ballpark. Okay. MEMBER OF AUDIENCE : Are you talking about degrees in Fahrenheit? MEMBER OF AUDIENCE : C. Matthew: C. MEMBER OF AUDIENCE : You’re talking Fahrenheit or Celsius? Matthew: C. I can shift into F if you want, but all our work is with C, so -- MEMBER OF AUDIENCE : (Inaudible.) Matthew: Yeah. So basically, if you have got about this much snow and it’s -- and it’s warm at the bottom, say, it’s maybe minus 10 at the bottom and -- and maybe it’s minus 20 at the top, you’re probably kicking into kinetic growth. The best way is to tell is to just take a hand lens and look. Sharp -- sharp edges, you know, you start to see these beautiful -- I mean, if it looks really organized like that, like something that -- that Steuben Glass Company cut, that’s kinetic growth. Right? You know, if you could see that sort of stuff, you’re into kinetic growth. And remember, nature’s not just imposing gradient over -- you know, it’s a dynamic system. So during the night it cools off, it’s cold, you know, we’re getting -- you’re seeing surface hoar overnight, right, glittery, big crystals at the top, you’re probably drive -- having very -- very strong gradients at night, and you’re driving kinetic growth. We can -- we will talk about that more. I love to talk about snow crystals, but -- MEMBER OF AUDIENCE : Do they consider the hoar frost and all of that part of the kinetic growth? Matthew: Hoar -- MEMBER OF AUDIENCE : Because it actually is a growth. Matthew: Yeah. Hoar frost, surface hoar, you know, on the stuff that forms on trees is an extreme form. It’s really -- MEMBER OF AUDIENCE : Oh, so it’s still the same? Matthew: Yeah, it’s still a kinetic growth form. MEMBER OF AUDIENCE : Okay. Matthew: But it’s separated out usually because the crystals are flatter and more feathery. But -- MEMBER OF AUDIENCE : Uh-hum. Matthew: Be -- they are -- they are -- the geologic term is euhedral. They have cleaved surfaces and everything that show you that hexagonal form, it tells you that it’s growing very fast. It’s a fast growth form.

Showing the snow bonds. Click here for image. Okay. One last thing about snow and then we’re actually going to get to climate. This is actually -- we -- we filled some snow with dimethyl phthalate, a carcinogen, so you don’t like to work with it, but it happens to not expand and not break the crystals and happens to have a different optic -- optical refracted index than snow. So then when we cut it with a microtome, which is a guillotine like thing, oh, we can see the snow grains. All that’s pretty interesting but the main thing is, look, they are all connected together. No surprise. Snow, unlike sand and other materials, because of its high vapor pressure sinters. That’s a big word and everyone should know that. Sinter. What sinter means is that if I take two grains of snow and I touch them together and I hold them there, even if it’s cold, little molecules will wander around through the volume and the edges and they will eventually bond the two together. That’s why the snow that falls off your roof, the next day when you go out and kick it, it doesn’t -- it’s not a powder anymore, it’s a solid. It’s called sintering. Metals do it, but ice does it really well. And that’s one of the things that’s very important about snow. It’s a sintering material, sinters faster when it’s warmer, but it sinters when it’s colder. If you live in a place where you want to build an igloo with your kids, what, right, and you can’t find a drift and you can’t find something to cut, you heap the snow into a pile, you come back the next day and now you can build an igloo, right? It’s sintered. It made bonds. Why are bonds important to climate? Well, we’re going to get to that, but bonds are where heat moves through snow, and that’s what we’re going to get to in a second. Heat likes to move through ice because ice is a good conductor, and it doesn’t like to move through air. So the fact that snow is not a loose, powdery material like sand makes all the difference in the world as far as insulation, as it moves through the bonds. So -- MEMBER OF AUDIENCE : The sintering properties, does that mean because it’s close to its melting point? Or is that something different? Matthew: Well, that’s a -- you know, I don’t want to answer that because I don’t know precisely. In large measure it’s because it’s a highly polar molecule. When I showed the tetrahedron, right, H2O, but you get the two minuses hanging out there, this is a polar molecule. It’s why water can rust stuff. It’s an extremely polar molecule. And so it’s got strong bonding -- it’s got strong attractive forces, and that leads to sintering, I think. It tends to make the molecules mobile. That’s a -- that’s a real general and kind of BS answer and I’d have to -- I’d have to look into it a little better to tell you exactly why, but yeah. All these properties imply a very active substance.

So it snows and we get this layer cake, and we’re moving, and we get all these things. Click here for first image.  Click here for second image. And I think I heard as I came in you guys were measuring depth and density, water equivalent, albedo, and so on. These are the properties of snowpack.These are the three I want to focus on because these are the three where the snow begins to actually affect climate. Thermal conductivity, water equivalent, and albedo. These are the ones that actually act locally, im -- impact globally. Snow thermal conductivity is a fancy word to talk about its insulation properties. Snow is a wonderful insulator. It’s a complicated thing when you’re down at the grain level, everybody needs to think for a moment, pretend you’re tiny and you’re in a snowpack, so you’re kind of surrounded by this interesting made -- interesting world of ice crystals and air spaces, right? The heat wants to move through the solid matrix of ice and not so much through the air. Okay. That’s kind of what’s going on there. The physics are probably less important than to know this is an important property of snow, and very, very important property of snow for those of us who live here in Alaska because without it, probably life would be completely different. This -- it’s the -- it’s the property of the blanket that helps keep the ground warm, the lemmings warm, the ground from freezing too much. Without the snow, the ground in Alaska and the plants would be subjected to the very bitter temperatures in the air. But they are not. They are protected by this wonderful blanket.

Click here for image. As scientists, we use the word thermal conductivity to parameterize that blanket, how good is the insulation. High thermal conductivity means it moves heat fast and it’s not a good insulation; low thermal conductivity, good insulator. So does it matter? Yeah, it does. These are four different places where we had different vegetation, and the vegetation is directly related to the amount of snow. So in the shrubs we had about this much snow, and out on the sparse tussock tundra we had this much snow, and look at the difference throughout the winter. 15 degrees different, C. 15 degrees C. Close to 30 degrees Fahrenheit difference from one place where we have deep snow to where we don’t have deep snow. Do you think that makes a difference? Yeah. That’s like getting mailed down to Seattle or up to Barrow. It’s a huge difference, all because of the blanket of snow. Does it matter to plants and microbes and things? You bet. So the entire ecosystems in Alaska are geared to surviving knowing what sort of snow they are going to have on it because the thermal conductivity is going to protect them from the frigid winter air temperatures. So kind of get -- so that -- so make that point.

Collection of thermal conductivity data throughout the years. Graph by Dr. Sturm. Click here for image. So what is the thermal conductivity of snow? This is a mess, isn’t it? I don’t expect you to get too much out of it except this is a paper I wrote a long time ago. There’s a couple of neat points. The first is I wanted to find out what every other person had ever measured on the thermal conductivity. It’s a little hard to see, but Hjelstrom actually started measuring it in 1889. They actually translated all these papers, the ones that were not in English. And we got all the data and we plotted all the data and then the take-away point is a couple things. The first, look at the vertical axis, that K affect, that’s the thermal conductivity. The top, the higher that number, the poorer -- poorer an insulator, the lower the better an insulator. The first thing is it ranges over two orders of magnitude, a hundredfold. So that means snow can range from extremely good insulator to extremely relatively poor one. So that’s the vertical axis. So what we can see is the data spans quite a range, which means snow can go through quite a range, which shouldn’t surprise us, given what we saw in those crystals, in those bonds. It’s a very diverse material, no surprise it can have a wide range of insulating properties. The second thing in this, and I think some of you do measure density, look along the bottom. As the density goes up, its ability to insulate goes down. Dense snow is not as good an insulator as flat white, light, fluffy snow. So here’s something just to keep in mind. There are two types of snow in Alaska that all of you will impact that are good insulators -- they are the best insulators. One is light, fluffy, new snow that’s coming down without wind. Fairbanks has just got some wonderful snow like that. So that’s -- with lots of air in it. And the other one is depth hoar, the big kind of grainy snow you find at the end of the season. Pukak. Those -- those tend to be low density, low thermal conductivity.

Pathway of a layer cake. Click here for image. And the snow changes with time, the thermal conductivity. So this sort of -- again, we’ve got thermal conductivity. You can kind of see, this is actually a pathway we could follow through a winter of a layer cake of snow and ask how -- what’s its thermal conductivity doing as it’s changing on the ground, as it’s going up, coming down, and so on.

Click here for image. Well, let me put this all together now, now coming back to climate.This is actually somewhat hypothetical, though the data gets stronger and stronger each year for -- from our work, is this has to do with how Alaska might be changing as the climate changes. You start with maybe a little bit of climate warming, perturbing the shrub density. So we’re in a tundra area, we start to grow a few more shrubs, and I’ll show you that in a minute. I already showed you the deeper -- when you get shrubs, the shrubs trap snow and the snow gets deeper. And I showed you that as the snow gets deeper, it gets warmer, right? Why does it get warmer? Because of its thermal conductivities. So it’s a little hard to see these white things, but you see a drift, shrub drifting snow, and now it’s getting warmer because the snow is deeper. So the soil temperature goes up and the microbes love that. And they chew away and they make more nutrients, that’s what these two show, and the nutrients help the shrubs grow so they get bigger still. So the snow gets deeper, so the ground gets warmer, and so on. And so next thing you know you’re going from tundra to shrub. Why? Because of thermal conductivity of snow.

Changes in vegetation. Click here for first image (1949).  Click here for second image (2001). So we start from the grain and we can change a whole landscape. This is true? Maybe. 1949, it’s near the Chandler River. 2001. We’re back. Are the landscapes in Alaska changing? Very definitely. It’s warming, we are seeing changes, we’re seeing movement of trees north, and we’re seeing the tundra change. Is the snow playing a role? I certainly believe so. What little property? Thermal conductivity. The little grains and how they are put together have a big impact on how we might change a whole landscape. So that’s one reason snow’s important for climate. Give you one more shot at that. MEMBER OF AUDIENCE : What’s the -- what are -- what was the date of that last one? Matthew: ‘49 and 2001.

Soil Pit: snow effects the active layer. Click here for image. There’s another place that snow plays a big role. I won’t go in as much detail, but this is a picture -- my wife looked at this and she said, well, how do you know where to put the white lines? I don’t. Actually, Gary Michaelson and Chen Lui Ping, who are soil scientists, did this. So we just have to accept that the active layer goes down to about 60. I don’t really know that, but this is a typical soil pit in Alaska and we’ve got the organic layer and an active layer and permafrost. That’s probably true for virtually where all you folks are from, right? But what’s the snow do? Well, the snow -- the snow determines as much as summer warming how thick the active layer will be. And one of the critical thresholds that’s going to occur in Alaska if it continues to warm is some winter the active layer won’t freeze all the way down. And there will be a little layer -- I don’t if I can -- let’s see. Well, no, that’s not what I wanted to do. Well, I’m not sure. Well -- no, that’s what I want here. No, not that. Okay. I won’t be fancy. At some point, just above the bottom of the active layer we’ll have a zone that doesn’t freeze. That’s call a talik. Why would that be important? Well, let me put it this way. Right now in many places in Alaska, during the winter the active layer freezes completely, the ground water stops flowing, and the system is sort of hydrologically dead for the winter. Then the summer thaws and we’ve got an active layer. As soon as you have a talik, that system has an active ground water system all winter, and you bet that’s going to have a big change in how things function. What will control whether we get taliks? Warming climate and snow insulation are going to be two of the big issues. So once again, thermal conductivity of snow, its insulation property, is going to have a big impact on whether the active layers in Alaska freeze solid every winter or whether they remain thawed at their base because the winter cold wave can’t get down far enough. MEMBER OF AUDIENCE : How do you spell tal -- talik? Matthew: T-A-L-I-K.

Everything is linked together. Click here for image. I tried to put that together in this very confusing diagram, but the main point is, is everything is linked. This shouldn’t come as a surprise to a group like you, but -- so what you can see is I sort of showed snow trapping and, you know, increased shrubs, that’s the kind of green loop. There’s other pieces, but the brownish tan loop is the one that what happens if you have winter warming and you start to add snow, you can change your permafrost temperatures, you can move towards discontinuous permafrost. So once again, just that insulation value of snow is playing a big role in where our permafrost is, whether we have year‑around functioning ground water systems or not, and ground water systems determine what our vegetation and ecosystems are like. Okay. So -- so that’s one aspect of snow that’s very important for climate, the insulating blanket of snow, that wonderful white blanket that keeps and protects us from cold weather and warms our ground.

Albedo is the reflection of the sun on the snow. Click here for first image. Click here for second image. Let’s go to the other, the really big one. Albedo. That’s a fancy word. It doesn’t show up quite as well. I like this picture, but notice the snow is a little bit shiny in the background and there are two colors in this picture, white and dark. White and black, right? We all know this. Go out on a warm day with a black shirt and your shirt warms up. Go out on the same day with a white shirt and you won’t feel that warmth. What we’re talking about with albedo is the ability to reflect sunlight. Very simple. You’ve got incoming solar radiation, and some of it hits the surface of the snow and gets ricocheted back to space, and some gets in and can warm the ground. Snow is one of the all-time champions at reflecting solar radiation. Albedo is -- is expressed as a fraction, right, so if you reflected all the radiation that was coming in, you’d have the -- the number 1. If you absorbed all the radiation, you’d have the number zero. Snow gets up to .9. New, fresh, shiny snow, the day you walk out in the morning and you’re, oh, where are my sunglasses, why is -- why do you need your sunglasses on that bright sunny day? Because all the solar radiation is being reflected right back to your eyes in the space. Albedo of nearly .9. Look at lakes and forests. .1. What’s the ratio there? 9 to 1. 9 times as much energy can be absorbed with a low albedo as a high albedo. Nine times. That’s usually extreme, but we’re talking about major shifts in the amount of radiation available to be absorbed, and snow is one of the all-time best ways to reflect it. MEMBER OF AUDIENCE : Is sunburn why in the wintertime? Matthew: Oh, sunburn on the bottom -- on the roof of your mouth, on your nostrils. Why? Because of that ricochet.

Measuring the albedo throughout a melt season. Click here for image. These are some plots from data we took at Council. It’s -- it’s awful hard to see. The important thing isn’t so much the various curves as we were measuring the albedo across the melt season. So all of these curves have that kind of cliff as the snow melted away. Look at the numbers. .8, we’re moving along and it’s .8, and then it melts the snow and we’re below .2. Four or five -- it’s a five-fold change in energy absorbed. Okay. So this is what we mean by albedo. Snow reflects pretty good. Important to climate? Yeah. Really important.

Dave Robinson's website:  Click here for first image.  Click here for second image.  Click here for third image. Matthew: Dave Robinson maintains this website. It’s a wonderful website that tracks snow cover in the Northern Hemisphere through time. And he’s got it archived. The scales down there are dark blue all the way up to white. White is no snow, dark blue is 100 percent snow cover, and it could be kind of patchy snow cover. And this -- this particular period is from August. So it’s August, right, we’ve finished the melt season, summer’s gone. How much of the Northern Hemisphere is covered by snow? Basically just Greenland. About 2.7 million square kilometers. That’s covered by snow. So that’s white and has a high albedo. October. This is October of last year. 23 million square kilometers now. 10 times more of the Northern Hemisphere’s covered by white stuff that reflects 4 to 10 times as much energy as the ground that it covered. Okay. March, last year, 41 million square kilometers in the Northern Hemisphere are now covered by a reflective material. I haven’t done the math, I don’t actually think you need to, all you have to think about is what happens if you take 41 million square kilometers of the earth and you change its albedo from .1 or .2 to .7 or .8. What happened to all that solar radiation? It went back to space. So Earth tends to stay cool. Is this important for climate?

Feedback loop. Click here for image. Yeah. This is the grand-daddy of all feedback loops. If the climate is warming, snow extent will be less, and it will -- it will last a shorter period of time. Everybody believes that, right? Yeah. MEMBER OF AUDIENCE : Okay. I guess I missed something. On the -- on the previous one where you were talking about thermal conductivity. Matthew: Yeah. MEMBER OF AUDIENCE : I thought there was a slide there that said when the -- when it’s warmer, we’re going to get more snow in the wintertime. If our -- if our winter temperatures rise -- rise, then we’ll have more snow. Matthew: I actually didn’t say that, but that’s generally hypothesized. MEMBER OF AUDIENCE : I was thinking that I had seen it on the screen. Matthew: Yeah. I’ll -- I’ll come to that in a second. There’s -- there’s actually a little bit of a conundrum here in that thermal conductivity and albedo could potentially work against each other. MEMBER OF AUDIENCE : Okay. Matthew: So I’m not actually saying how these work together. Don’t -- don’t think about them working together, these are two separate things about snow that affect climate. We’ll talk about how they mesh in a moment. MEMBER OF AUDIENCE : Okay. Matthew: And -- and the issue of whether we’re going to get more snow in a warming climate is a very interesting issue that there are many different opinions on right now. So -- but -- but keep them separate -- MEMBER OF AUDIENCE : Okay. Matthew: -- maybe for right now. Just think about them as separate processes, then you can begin to ask, well, what happens when I begin to think about both of them? So the albedo issue is independent from the thermal conductivity is -- is here’s the basic premise. If a -- a warming climate tends to mean less snow for a lot shorter period and that exists for shorter periods of time, that means there’s more of the earth that’s dark and absorbs solar energy, which means the earth tends to warm up more, which means there’s still less snow. So here’s another feedback loop. I showed you one of the shrubs. This is the one that relates to albedo. And this is probably the grand-daddy of all ways that snow impacts climate because it’s this great, shiny mirror that can reflect snow -- sun from the earth.

Sea ice extent is shrinking. Click here for image. It’s also true on the sea ice. I know most of you are not -- how many of you are working in coastal locations? So okay. So you’ve got sea ice and the sea ice is covered with snow. The same thing is happening there. The background picture, my -- my friend and colleague, Don Perovich, took it, it’s a vertical view of sea ice in the spring. So the light blue are the melt ponds on the ice, and the dark blue is the ocean. I just love the picture, but more important is the inset. The sea ice extent is shrinking. I think everybody’s heard that. The red line is where it ought to have been in September of 2002, and the colors tell you where it actually was. There was a whole bunch of places there wasn’t any sea ice. Let’s go back to the albedo again. Sea ice is almost as shiny as snow even if doesn’t have snow on it. And if it has snow on it, it is a snow-covered surface. This albedo is like .7, ocean is .1. Seven-fold more heat absorbed if you expose ocean instead of ice.

Fresh water is our life blood. Click here for image. Okay. Then the last of the three I just wanted to talk briefly about, and then I’m going to open up to questions, were water resources. I -- we all know that fresh water is our life blood. And somewhere between 50 and 90 percent of the fresh water in Alaska comes in the form of snow. All right? Some of the rivers -- it can vary, but certain rivers in Alaska, say, North Slope rivers, 75 percent of the runoff that runs down that river came in the form of snow. So I don’t want to get into the details because this is even more complicated than albedo and thermal conductivity. Let’s just say that snow plays an enormous role and will, and our water resources will change as the climate changes the snow cover. And I love this picture just because there’s the snow and it’s turning into water. And that’s -- that’s the third aspect of snow that’s going to affect climate that everyone should be aware of because Alaska works this way. We stockpile our water all winter, and then we let it all loose in one grand thing called break-up. That’s a little different than they do in Iowa where they let it run off all year. So -- MEMBER OF AUDIENCE : What was that percentage again? Matthew: Well, you know, it varies from one creek and one river to another. It’s typically somewhere between 50 percent of all our water that runs down that river and 80 percent, is -- came in the form of snow and was released during break-up. You know. So, you know, you can think of a lot of them but, you know, that’s kind of the range we know.

Dr. Sturm's children take snow samples. Click here for image. And so I think I’m just going to end there. I know you guys know about these probes. These are my kids. They are no longer in Weller, they are a lot bigger, unfortunately. They don’t want to go out and do science anymore with me. But I think most of you know what this activity they are doing is. And this is at Ivatong (phonetic). They have spent a lot of time, actually, measuring the snow. So I -- that was -- that was a very quick overview. MEMBER OF AUDIENCE : I don’t know what the activity is. Would you explain to me. Matthew: What -- what they are doing? MEMBER OF AUDIENCE : Yeah. Matthew: These are temperature probes and we want to know what the temperature is at the bottom of the snow. Remember the thermal conductivity and we said, oh, the deeper the snow, the warmer it is. That’s what we’re measuring. So we stretch the tape measure out. Eli’s actually right over a gully where there’s actually shrubs that are totally buried in the snow. We -- we expected it to be warmer there. And he’s been pushing these in down to the bottom of the snow. And he’s got a digital meter there and he’s checking the temperature. So we’re actually mapping the temperature at the bottom of the snow and confirming something we knew quite well, which is it’s very warm where that deep snow is right where he’s standing. There's kind of in a little bit of a drainage there. If he came back in the summer, he’d actually probably be in the drainage. And he’s doing one other thing that is completely fake, which we never let him write in the field book. My daughter’s handwriting is good, his is miserable. So this is the stage she told him to do that, and then she took the book back because it would be unreadable if he had recorded the notes. So let me -- let me stop there, then, and -- and we’ll just -- the rest should be questions. That’s kind of an overview. And so I guess there are a couple big areas. First, if you’re not convinced that the climate’s changing in Alaska, we should talk a little bit about that. Then any questions you have, whether it’s about snow crystals or snow and climate. And was that what you wanted me to talk about?

Matthew: Don’t be bashful. I don’t stand at any -- I’ve been in classrooms in Buckland and Selawik, in Ambler. I’ve been all over the state. The kids ask lots of questions, you guys should, too. Don’t -- don’t be bashful. Go ahead. MEMBER OF AUDIENCE : There are a couple of things that I’ve read over the past few years. One is there was a lot of extra volcanic activity in the Pacific Ocean, and another one is that there’s always warming before an ice age and things like that. Matthew: Yeah. Let me take the second. I don’t know -- there has always been a lot of theories about climate change and volcanics. When -- what’s the Filipino volcano? That was a -- MEMBER OF AUDIENCE : Oh, yeah. MEMBER OF AUDIENCE : Pinatubo. Matthew: Pinatubo. You know, we were able -- not my group, but groups were able to track the cooling of that, that lasted about three years. So the theory goes like this. And if you -- if volcanoes blow a lot of aerosols into the -- into the troposphere and the stratosphere, they reflect sunlight, it cools. And there have been periods geologically when there were much more volcanic activities, and some people wonder if that’s not a climate trigger. For sub -- sub-oceanic ones, I don’t know how that works because they -- volcanoes also release a lot of gas, CO2, methane, and so on, so that would bubble up out of the ocean and add to it. You know, I -- I don’t know the literature right now on that. The second one, though, is ice ages and -- and warming and cooling. Earth has -- there are a couple things that have -- we’ve learned in the last 15 years that are really exciting and frightening at the same time. Independent of humans, we know that the Earth’s climate system can change very rapidly. The Greenlandic core showed us that somewhere between tens and hundreds of years, you can get these large shifts, switches. That’s the natural rhythm of Earth. The system is complicated enough to do that. Whether you get warming prior to cooling, I guess almost by definition, of course, you would, right? You know, Earth is rarely stable so you’re either warming or cooling. We don’t have long stable periods, so it would be unlikely that the run-up weather to an ice age or warming period would be something other than the opposite. But I don’t believe there’s a lot of evidence right now, you know, that would say we know the pattern. A lot like trying to track the stock market, you know, okay, it’s coming up, that means it’s going down, I’ll sell short. We don’t know that right now. What we do know is study after study seems to show right now two things are fairly clear: One is the atmosphere, the current atmosphere is enriched in CO2, the levels that are -- have rarely been achieved in many, many -- in millions of years. We have a very CO2 rich atmosphere. And of course, humans may be a major driver of that. And the second is we’re experiencing temperatures that are warmer than, what’s the last, you know, thousands of years. So -- and third, things like the sea ice, which are now in record small amounts, respond at very high rates. In other words, if you want to know how much sea ice there is, you don’t have to go back 10 years, you just have to ask what happened last year and the year before. So some of the records like the sea ice are telling us that it’s not what’s happening right now as well as what’s happened in the past few decades or hundreds of years that -- that we’re moving into environmental conditions that tell us it’s very warm. Some people would sort of propose that, well, yeah, then it’s going to go the other way. And Earth could still surprise us and have natural cycles that overwhelm the cycle we’re in. That’s the million dollar question. If we -- if I knew the answer to that, I probably wouldn’t be here right now, I’d be advising other people. But all of the signs show, you know, virtually all of the environmental indicators and the actual temperature indicators are all on this up-rise, and we -- we Alaskans are right there in the middle of it. You know, we’ve got the fast -- we’re seeing the strongest warming. If we lived in Eastern Canada Arctic, we couldn’t say that. They’ve been actually cooling because it’s kind of a coupled nature to this thing. But Alaska, Siberia, Chukotka, you know, these have all been warming faster than the rest of the globe. So it’s kind of a roundabout answer to your question. There is no certainty in this game because Earth has a very complex climate history and probably will continue to do so.

Matthew: Other questions? Sure. MEMBER OF AUDIENCE : Yeah. How -- how do you look at the ice crystal -- the snow crystals without having it melt? Matthew: Okay. There’s -- there’s a bunch of different neat things you can do. What I do personally, I have a wonderful -- it took me years to find this. I have a little -- it’s a Nikon scope that I wear on a strap and it’s a stereoscope. So I just -- I just do it outside. There’s a -- there’s a couple ways you can do it that I’ve done with kids. If -- if you’ve got kids and it’s hard to get them outside and they have got to get their clothes on and as soon as you get them out in the snow they are all gone, go get a really big bucket of it and bring it in, it won’t melt that fast, then use your hand lens in the classroom. All right. If the bucket’s big enough and you’ve got it heaped up, the top will start to melt, but you can always sort of dig up some new stuff and if they are a little bit quicker. What I’ve always seen for the younger kids is give them a hand lens and they don’t know how to focus it. That’s always struck me as the biggest problem. You know, they don’t know how to find the snow with that. But you can work inside instead of outside and that’s better. Another way -- so it depends on the age of your kids. Another way that really works well, like your jacket’s perfect. You get a piece of that cloth, stretch it and glue it on a board about this big, and just wait until a day to where it’s snowing. Get the kids outside. You don’t even need the board, by the way, your sleeve would work. Go outside with your kids, let the snow land on your sleeve or this board, and look at it outside while it’s landing. Because one of the things that makes it hard for kids to see the crystals is when they are all glumped together. And nature lets it fall on your jacket individually. You know, the days when you can see the crystals on you, that’s when to have them look. That’s a great time because they can get focused on one and they don’t -- they don’t see them all overlaid. So being opportunistic and, oh, we’ve got a light snowfall going on, let’s go outside now. The bucket works; it’s not the greatest way. And I have some really bad -- I was at Tanana here, and I said, let’s get a bucket of snow. And the class had 20 kids, and 9 of the boys were gone. Then they got locked outside, they never showed back up. That’s what, okay, I gave them a bucket and they were -- that was it. But you guys know all about that, so I don’t need to tell you. But working in the cold can be hard. You know, so it’s -- so the thing is to sort of find an environment. Railings on -- on decks around the schools can be a good place, you know, where they can get close with their hand lens. Hand lenses are hard. If your school has old style, low power stereo-microscopes, those are really good. Monocular scopes tend to have too high of power. That’s usually where people go astray because it’s 30 X, and that’s too much. 5 to 10 X is sort of what you want. Big magnifying glasses aren’t bad, either. One other hint on this, then. Snowflakes that fall out of the sky are very fragile. Where -- where are you from? Where are you -- MEMBER OF AUDIENCE : Barrow. Matthew: Okay. At Barrow, the way I would do it, if I wanted to get them to look at crystals, is I’d wait a little bit longer, and then I’d dig in between the tundra tussocks, and there the depth hoar is growing big. And those crystals are bigger and tougher and easier to separate than the crystals falling out of the sky, and they are easier to look at. And big magnifying glasses rather than hand lenses will work for those. Because the crystals are -- some are a centimeter. At Barrow you can find a centimeter or two. Some of the crystals are big enough they can see them without even a magnifying glass. And what age kids? MEMBER OF AUDIENCE : Kindergarten. Matthew: Yeah, for kindergarten, the bigger the crystal the better. The last one, and not appropriate for kindergarten, but appropriate for a little bit older ages, the day it’s snowing and, you know, nice, light flakes are landing on your sleeve, break a straw off a broom. Okay. Go out. You get some glass slides and some Krylon fixative or hairspray will work. You’ve got to do this in the cold. You flick the crystal you want onto the slide, you spray it with the Krylon. It had -- the Krylon had to have been outside so it’s cold. MEMBER OF AUDIENCE : And the slide outside. Matthew: Everything’s got to be cold. Yeah. Anything’s warm, it will melt it. Let it dry and bring that into your microscope. It’s incred -- it’s very easy. It’s surprisingly easy. Doesn’t take much. Manipulating the crystals is the hard part. The things that usually screw people up are they forgot to cool the bottle of fixative, so they spray it on and it melts the crystal. They forgot to cool the slide so they flick it onto the slide. Or it’s snowing too hard and they’re big glumps of crystals and they don’t lend themself -- nobody can see the snowflakes because, in fact, you have 30 snowflakes in a -- in a wad. So those all work. For kindergarten, though, the one I do that I like the best is if the kindergartners learned that there’s six points instead of eight, that’s great. A lot of the teachers run into problems because how do you make a -- cut out a six-pointed snowflake. And if I had a scissor and piece of paper I could show you. The secret is to how you fold it so you get thirds, and then you cut your crystal out. Do you do this as an exercise? MEMBER OF AUDIENCE : Yeah. Matthew: So you know what I’m talking about. MEMBER OF AUDIENCE : Yeah. Matthew: So you don’t end up with eight-sided crystals. MEMBER OF AUDIENCE : Uh-hum. Matthew: Does anybody -- MEMBER OF AUDIENCE : Right. Matthew: Right. Yeah. Just drives me crazy when I go into a classroom and they have cut out crystals and they’ve got eight points. Because -- MEMBER OF AUDIENCE : I don’t like eight-legged insects, myself. Matthew: Yeah. But I’ve got to remember how to do this. Let’s see. MEMBER OF AUDIENCE : Do you fold it in thirds? Matthew: I’ve got to cut a circle. Yeah, you cut it in sixths. So the secret, really, at kindergarten age is -- is trying to get them excited. My wife is a teacher. They are using air clay a lot and pipe cleaners to make six-sided things, and that’s worked pretty good for kindergartners. You know, they lay out the six points and then they build these kind of things that range from beautiful crystals to really weird looking things. I don’t know if I’ll get this on the first try, but...Let’s see how it goes here. That’s not really round enough. Okay. I think -- so you start with your circle. I’m going to do this once and see -- oh, yeah. You fold it in half, and then -- so everybody -- and then you -- I think I’ll do it so you guys can see. And then you bring it in until it’s half -- until you have them equal. And that gives you sixths, and the sixths give you thirds. So -- so I folded that in. And then I folded that in. And I’ll get six-fold symmetry now. So did that make sense? And now I... So if you want six-pointed. And if I come to your classroom, I’ll be so much happier if I don’t see eight-sided snowflakes. The amazing thing, this -- you guys, this makes sense to you. The kindergartners and the first and second graders know that, and by the time they get to fifth grade they forgot how many -- you know, fifth and six graders have no idea how many points and the kindergartners know that -- that it’s six. So we’ve got the six-fold symmetry.

Matthew: Other questions? MEMBER OF AUDIENCE : Yeah. I have one. Would you send us -- do you have Martha’s E-mail? Matthew: Yeah. MEMBER OF AUDIENCE : Will you be going back and forth? Will you send the longitudinal snow depth study and the Caltech websites so we can pass them out? Matthew: Yeah. But here -- the easiest way, search on Google on Caltech snowflakes, you’ll find them every time. MEMBER OF AUDIENCE : Okay. What about the longitudinal? Matthew: The maps? MEMBER OF AUDIENCE : Yeah. Matthew: That’s -- that’s a Rutgers snow -- search on Rutgers and snow and you’ll get that one. I can get you the websites but I’m not sure I have them here. MEMBER OF AUDIENCE : You can just E-mail them to Martha and she will E-mail them. Matthew: Yeah. There’s great resources on the web. And how many don’t know who Snowflake Bentley was? Okay. There is a guy in Vermont, at the turn of the century, called Charles Bentley. He was a poor farmer but an interesting guy. He kind of let his farm go, but he took photographs of snowflakes. He let them land on a board like we talked about, and he was one of the first. And he photographed these snowflakes and then made a book of them. He spent his whole life doing this. The farm kind of went to hell, but... And -- and they have now sort of made a museum at his house. There’s a kid’s book called Snowflake Bentley. And they have put out CD’s of snowflakes. These are real pictures of snowflakes. Many of them are on the web. So if you search out Snowflake Bentley, you can find him. And hundreds of his snowflake pictures are on the web. And then you can buy the CD’s. I bought one of the CD’s for, like, $20, and that’s, like, hundreds and hundreds of beautiful snow crystals. One thing to keep in mind that most people don’t realize is Bentley’s pictures are beautiful, there’s a white snowflake on a black background. What he had to do was photograph every snowflake and then cut it out with a scissor, paste it on a black piece of paper and rephotograph it. So when you look at his snowflakes, keep in mind how good this guy was with a pair of scissors. It was amazing. So Snowflake Bentley. And there’s a website for him, I’m sure you can find that, as well. So that’s the other, you know, places to find snowflake crystals. You know, it’s real easy. MEMBER OF AUDIENCE : They are all published in the book, too. Matthew: Yeah, there’s a great big book. MEMBER OF AUDIENCE : They can all have access to it. Matthew: A lot of the teachers are teaching the Snowflake Bentley, the younger grades, they read the picture book and the story about him. My -- strangely enough, a very close colleague that I do my shrub research with lives, like, within a few -- his farm in Vermont is within a few miles of Bentley’s. And he actually knows, sort of, some of the old family. But -- so that’s -- that’s where you can find those resources. Great -- there are just great resources on the web for snowflakes. The Caltech site has a whole tutorial. MEMBER OF AUDIENCE : Talking about snowflakes, I teach kindergarten in Atqasak. Matthew: In -- in where? MEMBER OF AUDIENCE : Atqasak. Matthew: Atqasak. Okay. MEMBER OF AUDIENCE : Whenever it’s snowing the kids always want to see what they are -- shape is. We take the paper out (inaudible.) Matthew: Oh, good. MEMBER OF AUDIENCE : Then (inaudible) the paper (inaudible) will see right away. There’s different -- it always melts. And one thing that -- Matthew: Did you -- you got to put the paper outside for a while first. MEMBER OF AUDIENCE : For a little while, yeah. Matthew: Yeah. You’ve got to -- MEMBER OF AUDIENCE : (Inaudible.) Matthew: Good. MEMBER OF AUDIENCE : (Inaudible) -- see right away. Matthew: Yeah. MEMBER OF AUDIENCE : And last, like, March or April (inaudible) my house. From my house to the school. And the snow had fallen, but I saw the snowflakes on the ground and they were like foams. Matthew: Like what? MEMBER OF AUDIENCE : Foams. They were like foams. Matthew: Foamy things. Yeah. MEMBER OF AUDIENCE : (Inaudible) our aide that takes pictures to take a picture of them, but (inaudible). Matthew: What that -- I think -- I think I know what that is, is when a snowflake begins to fall and it’s coming down, occasionally there are other layers in the atmosphere that are moist and there’s actually liquid water. So instead of its frozen -- and when the snowflake comes through a liquid water layer, it look -- we call it riming, and it gets fuzzy. It looks like a fuzzy snowflake instead of a nice, crisp one. It would look like -- if it rimes enough, it will look like foam, just like you said. And so that -- there’s yet a third site -- there was a Japanese man who studied snowflakes, his name was Nakaya. And he believed that if you looked at a snowflake, it was a messenger from heaven and it told you what the heavens were like, and he was right. So when you see a snowflake and it starts up in the cloud, and of course, we don’t have any clouds today, but -- and it falls down, the history of it falling to the earth actually changes the snowflake. And so what you were seeing was a snowflake that had started like one thing, fallen through a different layer and different sort of moisture, then gotten to the earth. And so Nakaya’s goal that he did quite well was to figure out how to interpret that. I guess there’s a -- there’s a museum to him in his -- in Hokkaido, kind of almost a shrine that I’ve seen pictures of that I’d love to go there.

Sidney Stephens: I -- when we -- when we talked once, it was Bill had given these rave reviews about your presentation where you talked about changes that you’ve been observing in snow-up and snow-down? Matthew: Oh. Sidney Stephens: Could you talk a little bit about that because -- Matthew: Yeah. Let’s see. I just want to get my thoughts together. I don’t know a lot about it. I mean, that’s the first thing is -- is let’s take temperature. Right? We can record temperature and then we can ask whether it was warmer last year or colder. Temperature is simple, it’s just a number. And 5 is bigger than 4. So -- so that’s easy to do. But when we start to talk about changes in timing, fancy word, phenology, it gets a little bit harder. For example, if it snows in the fall but it only snows about this much, and then nothing happens, is it -- did it -- do we call that the start of snow when it first snowed, or do we wait until there’s a really serious amount of snow? Well, for albedo, that first snow is important; but for thermal conductivity, the thickness is important. So the two are different. So it’s -- it’s harder but more important to talk about changes in timing. And my -- my understanding is that’s sort of where you’re headed anyway. So it’s a challenge because it’s no longer as easy as saying 5 is bigger than 4. Some judgment comes into it in saying, well, yeah, the first snow was September 12 th, but we got just a skiff of snow and then nothing happened until December. That’s a very different story than if the first snows was October 12 th and it dumped two and a half feet. And yet if you compare the dates, they might be the same. The same is true on the other end of the season in melting. So I -- I guess the first thing I would say about that is that as soon as we leave behind simple things like temperature, we get into a much more complicated system of tracking things and more human judgment is required and cleverness of how to do it. The second thing, though, is that’s more important than temperature. It matters more when the snow comes than whether it’s a cold winter. For example, if I’m -- if I’m a microbe in the soil and I like to stay warm, the best possible thing that can happen is that it rain like crazy, you know, August and September so the ground is saturated, and then that just turn to snow and we build up, you know, 20 or 30 inches of snow. I’m going to be just warm and toasty all winter, compared to a winter in which it’s dry in the summer and the snow doesn’t come until December. Even if that second winter is much, much warmer than the first one I described, the microbes will be much, much colder. So for -- for a lot of the ecosystems we’re thinking about, whether it’s soil, plants, voles, these -- these all depend more on the timing of the snow coming and going than they do in the actual winter temperature. So this has been a fairly cold winter in Fairbanks, but we have this amazingly good snow. The ground is -- we’re not going to have any septic problems, septic systems freezing this winter, it’s that simple, no matter how cold it gets because we’ve got a good snow cover. Whereas last winter and the winter before where there was miserable snow cover but fairly warm temperatures, froze -- did freeze lines. So the issue of timing of the snow coming and going is absolutely essential. We’ve avoided it more because it’s harder to deal with, not because it’s so essential. It’s just not as easy as comparing 4 and 5. Sidney Stephens: And but do you have -- do you have thoughts, then, about -- I guess the background for this is that what -- one of the things we’re trying to do is we’re really trying to help people think about what the local issue is and observations in the community means and we’ve used the book protocols a lot because there’s a really good match-ups there. Matthew: Uh-hum. Sidney Stephens: But -- but what a lot of people talk about is things like freeze-up and break-up times, timing of snowfall, and -- and its relationship to travel and so on. So do you have ideas about how a classroom might proceed to -- Matthew: Yeah. Sidney Stephens: -- to think about some of these things? Matthew: Yeah. I need to draw something, though, and I’m wired. Bill Schneider: We can bring that here. Matthew: Bring that here. Yeah. How many of your kids can deal with pattern? Patterns. Forget nature. I mean, pattern. I mean, you know, patterns of things, shapes. And of course, they all can. And what we’re talking about is pattern recognition. So there are two things that come into this, in my thoughts. I just need -- need a -- need a -- something to draw with. That will be fine. Thanks. I’m just going to make snow depth here. And we’re going to make this summer. And winter. And spring. Okay. Which is time down here. This is -- this is this year for Fairbanks. I -- I don’t know, I haven’t been travelling much in the state so far this winter, though I’m going to be travelling quite a bit later so I’ll probably get to know a little bit later, but... That’s the pattern we’re sort of going through now, the summer -- summer, and then the snow came and we got lots of it, and we’re picking up more but not as fast, and then it will melt. Right? So that’s one pattern. I think last winter probably looked like this. Those look different? Can you -- can you recognize the dif -- so this is -- we had a little bit of snow, melted snow, melted finally. When people are talking about the -- noticing these things, what they are talking about is patterns. And the secret is you’ve got to get the patterns down to some way that you can -- can actually begin to recognize them. And I think graphing is one easy way. What -- but there are critical sort of threshold points you’ve got to somehow identify that you want to be aware of. And it’s not -- it’s not good enough to just say, well, the snow came on this date, it’s sort of got to be the snow came and there was this much of it. So the secret about snow-up and break-up -- and I drew these melting at the same time, I’m not sure that’s right -- is somehow capturing the essential difference in these patterns because there’s a vast difference in climate and response to ecosystems to the patterns. So that’s what you want to be headed for in some way. And -- and the, you know, native elders and people in the Bush, what they are talking about are patterns, as well. You know, and they are saying, well, the break-up came at a different time and in a different form. So it’s not just getting the timing but the form. If it were me, as a scientist, with a -- kind of the way I think in numbers, I would literally, you know, I would assign functions to these. But I don’t think that’s how you want to go with your school kids. I think what you want to do is sort of get from the data, try and distill the patterns. What I’ve been thinking about, and I’m actually working on this now, was starting to turn these into very simple diagramatic patterns and then calling them classes. So one way I could see doing it, and this is -- I haven’t done this yet, you know, there’s -- there’s what I would call the step pattern for winter snow-up. That’s one pattern, right? Here’s another pattern. A very -- you know, and what actually happens in nature could be sort of classified as, you know, you could come up with a set of classes of patterns and just sort of say we had pattern 1, 2, 3 or 4 this year. So the first thing would be to identify those. And then, of course, when it comes and when it goes would also be in there. So that’s kind of how my thinking’s gone. It’s not mature thinking yet. I’m -- I’m actually -- what I do -- what I have to do for a living is develop models and actually turn this into numbers and write papers, so I’m -- I’m sort of thinking of it in terms of mathematical functions. But if I were dealing with a bunch of fourth graders and I could get them to sit still for a few minutes, they can grasp this just fine. And they might have a more clever idea how to do it. You know. So that that’s -- but this is what you want to get before them. And it requires that they understand sort of a graph that has something versus time. Then -- for most -- by the time you’re in fourth grade, a lot of them could pick that up, I would think, can’t they? Some -- some will have trouble but a lot of them could. MEMBER OF AUDIENCE : A model could be best -- line of -- line of best fit, simple enough to translate that, then -- and then sort of an operational definition, you know, to fit the classes. Matthew: Yeah.

Matthew: The thing that sort of underpins it comes from my talk is it matters whether you have -- you know, it’s not just when it got here, but whether it’s real thick or real thin and how long it’s there. The essence of time, as soon as you move into the area of break-up and freeze-up, the essential essence is time that you have to get in there, how long was it a certain way. You know, this is what -- when people talk about travel and what they are saying is I couldn’t get there until too late. Right? And that’s -- that’s what we’re hearing. Just an anecdote, I was working out of Council near Nome for quite a few years, and we had one of these patterns, but what was interesting is when the Niukluk River froze and there was no snow, so they could drive pickup trucks all the way to White Mountain. They did. They drove them all -- I mean, it was amazing. You could drive from -- you could drive from Nome all the way to White Mountain on the ice because there was no snow to deal with so there was actually an advantage. If you get break-up and snow comes late, you actually get some advantages. So that’s -- that’s kind of my thinking, but I -- you know, that’s -- I’m not sure I could give you a hard and fast, this is how I’d do it. Sidney Stephens : No, no, but that’s good. Bill Schneider: I think, though, if I can make a comment here. One of the questions has come up with the reindeer research that I’ve been doing out in the northwest, and I think Kumi talked to you about some of this. Matthew: Yes. Right. Bill Schneider: One of the problems, the herders are saying that the snow is coming later, and that in the spring, they are having trouble getting to their herds, too. So as -- there’s a human dimension here that where you have transportation with snow machines being able to cross rivers, having sufficient snow depth to get there -- Matthew: Yeah. Bill Schneider: -- and being village centered focus, how do you get to your herds when you need to get to your herds. Trying to correlate that with -- with snow depth, it’s -- it’s very hard to do. But -- but the -- but I think the important thing is to look at how people in the community do what they want to do when they need to do it. Matthew: Yeah. Bill Schneider: So putting the human dimension in, I think, will be -- will make it real to your kids. You know. If father or grandfather can’t get to where he needs to get when he needs to get there, or when he perceives he needs to get there, then that hits home. That’s where the rubber hits the road. Matthew: But the thing is to challenge them at that point and say what is it about the conditions that make grandfather not get there? Is it the snow depth, the lack of the river freezing? Get -- get more specific, then, and make -- make them get to the bottom of why because maybe grandfather can’t get there because his snow machine’s broken. Bill Schneider: Yeah. Matthew: Or he’s got a snow machine that needs -- that has high tracks that don’t -- that seize up, or it’s a fundamental sort of the snow didn’t come until late. What you’ve got to do is sort out so you find a commonality in, well, last year could he get there? No, he couldn’t get there last year. For the same reason or for some different reasons? Then you begin to see how the human dimension is intersecting with the natural sort of cycle. Bill Schneider: And the -- and the particular routes that they are taking. Matthew: Taking. Yeah. Bill Schneider: And how those are impacted by rivers or snow depth in certain valleys, that sort of thing. Matthew: Yeah. Like the trips we would take from Nome to Council, you know, you drive on the road until there’s enough snow. And the road’s kind of a miserable trip, but you can get there. And so the routes shift all the time in response to these sort of patterns. If the ice freezes up -- just here I have a cabin I go to, we’ve got lots of snow, but we had incredibly wet fall, the ground water is high, the rivers haven’t frozen very well. So I couldn’t -- I was having trouble getting there, not for lack of snow this year, but for lack of ice. Plenty of snow. So -- so you want to sort that out as you do this human dimension part. You want to figure out, okay, what is it exactly that -- that’s left that.

MEMBER OF AUDIENCE : I have a question back to earlier. Matthew: Sure. MEMBER OF AUDIENCE : About how when you have this reflective surface that’s reflecting more of the solar energy back. Matthew: Right. MEMBER OF AUDIENCE : And that that -- that warms us up. Is that what we’re saying? Matthew: No. MEMBER OF AUDIENCE : What’s the -- Matthew: All things being equal, if -- if I have snow versus something darker, that cools us down. MEMBER OF AUDIENCE : Oh. Matthew: Yeah. Albedo -- albedo works towards cooling. MEMBER OF AUDIENCE : Okay. Matthew: So if I get -- if I get less snow and I keep the snow shorter -- MEMBER OF AUDIENCE : So the atmospheric temperature will be lower if you have more snow-covered surface? Matthew: I think the way to think of it more is just kind of an exchange. It’s not so much -- don’t think in terms of temperature, just think, there’s -- there’s earth. MEMBER OF AUDIENCE : Okay. Matthew: And a bright shiny earth, much of the solar radiation goes back out on earth as cooler; and a darker, blacker earth absorbs more and it’s warmer. Okay. That’s -- that’s the general principle. MEMBER OF AUDIENCE : Okay. Matthew: Climate warming tends toward a darker, blacker earth. MEMBER OF AUDIENCE : Okay. Matthew: That’s why climate warming with -- through albedo, it’s actually the reverse. Albedo -- high albedo promotes cooling. MEMBER OF AUDIENCE : So we’re getting less and less snow-covered surface. Matthew: Yeah. You can demonstrate this to your kid. We -- we live with it every time we go from summer to winter in Alaska. All you need to do is notice you’re walking around in shirt sleeves and then it snows overnight, and the next day’s not any colder and you’re colder. And then the temperature starts to drop. We see it year after year in Alaska, that as soon as we get a snow cover, our temperatures start migrating down because all that solar energy that was being absorbed by the white -- the dark tundra, now isn’t. So we actually experience an albedo cooling seasonally here. And -- and the reverse is, you know, in spring we experience the other one. The snow melts and it’s warmer. Right? Because go lie down and -- in black tundra. Wow, this is warm stuff. Try and do it on the same snow. Well, this isn’t. So we live with this all the time. I -- I haven’t ever done this with kids but I would -- you know, white and black sweatshirts, so I -- you know, send the kids out in a white and a black sweatshirt, kids outside, and you can probably do your own little albedo experiments. Because we all know -- you know, I love wearing -- all my outdoor gear is black. Everything I own is black because it’s great. It -- you know. I can wear less of it it’s sunny. You know. I -- I don’t know how that plays out in other garments, but you can demonstrate albedo to kids quite easily. MEMBER OF AUDIENCE : Okay. The reason I was asking -- Matthew: Yeah. MEMBER OF AUDIENCE : -- this was because when you said that I was -- I was -- you know, I -- I am encountering the term for the first time, basically. Matthew: Yeah. MEMBER OF AUDIENCE : And so when you were talking about, you know, when more of the earth is reflective, then -- or have -- if -- has a higher reflectivity, then -- then we’re going to be reflecting warmer solar rad -- Matthew: Right. MEMBER OF AUDIENCE : -- radiation back into space. And I was thinking, well, but -- Matthew: That will cool us. MEMBER OF AUDIENCE : Okay. Matthew: Yeah. MEMBER OF AUDIENCE : Because I was thinking -- Matthew: No, no. MEMBER OF AUDIENCE : -- you know, if it doesn’t get reflected, then -- Matthew: No, no. MEMBER OF AUDIENCE : -- at that point the warm -- Matthew: Yeah. MEMBER OF AUDIENCE : It warms things up somewhere? Matthew: I may have made it confusing by sort of switching my point of view partway through. I wanted to first get albedo, and then say what would happen in climate warming. MEMBER OF AUDIENCE : Okay. Matthew: In its purest sense, high albedo promotes cooling because it reflects energy. MEMBER OF AUDIENCE : So if we’re experiencing a global -- a global warming trend -- Matthew: Yeah. MEMBER OF AUDIENCE : -- like you’re saying we are entering this era where the temperatures are climbing, right? Matthew: Yeah. MEMBER OF AUDIENCE : Then can I assume, then, that -- that we’re getting less snow-covered surface? MEMBER OF AUDIENCE : Yeah. The -- the extent of snow cover is -- is declining slightly. MEMBER OF AUDIENCE : Okay. Matthew: And the duration. Remember, your -- MEMBER OF AUDIENCE : Okay. Matthew: You can integrate this over time. The duration, it’s not lasting as long. MEMBER OF AUDIENCE : Okay. Matthew: In fact, the trends are very clear for spring. Spring is coming earlier throughout Alaska. That’s pretty clear. Fall is less clear. We’re not -- it looks like fall is sort of still coming about the same time. Fall is pretty messy, too, right? I mean, it’s almost a two-month period when we can say snow-up occurs. But spring is definitely happening earlier and leaf out. MEMBER OF AUDIENCE : Okay. That makes sense, then. Matthew: Yeah, I’m sorry, I didn’t mean to confuse you. MEMBER OF AUDIENCE : -- confused a bit. I’m sorry. Matthew: Yeah.

MEMBER OF AUDIENCE : I think in comparison with many other parts of the country, in my opinion, (inaudible) here in August, the last winter -- Matthew: Okay. MEMBER OF AUDIENCE : -- we had snow from November into April, we had a lot of snow last year. Matthew: Yeah. MEMBER OF AUDIENCE : We had a colder and normal winter. We had no January thaw (inaudible) we had snow on the ground. Into April -- Matthew: Right. MEMBER OF AUDIENCE : -- we had a wet, cold spring before things warmed up. Matthew: Oh -- you’re opening the door to one of the more confusing parts of climate change, but I’ll take a stab at it. My colleague, Mark Serreze, is an expert on this. It’s called the Arctic Oscillation, or the North Atlantic Oscillation. But let me back up. The Vikings knew about this. Okay. This -- this sort of went this way. The Vikings knew that a bad year in Greenland was a -- was a nice year in Denmark. Okay. Nice years in Denmarks were bad years, and the reverse. Earth’s climate is not a static thing, it doesn’t just warm and cool. Everybody’s heard of the Gulf Stream, right? Big ocean, right? And we know that storms are cyclones and they track, and there’s -- and there’s the jet stream, right? So -- so keep these pieces in mind. It’s a very dynamic system. Okay. With that in mind, then, people have noticed that the Islandic low and the Azores high, if you track those, right, because typically, there’s a low pressure center over Iceland, and a high pressure center over the Azores. And if you look at the strength of the difference between those, that’s called the North Atlantic Oscillation. And when they’ve tracked that, they’ve discovered there seem to be two modes. And I won’t get into the technical details. But in one mode, Europe is getting warm air streaming up along with the Gulf Stream, and cold air is funneling down through Davis Straight over Greenland and Eastern Canada. In that mode, Alaska has warm air, we get -- we get this Pacific -- what people -- I’ve read about, it’s called the Pacific Conveyer Belt or the Hawaii Express. That’s what we’ve been in a lot of the years. So these patterns mean that invariably, even under warming climates, there’s going to be some places that are getting the cold return air. What you had in New Hampshire was exactly that. We were getting unprecedentedly wet, warm weather in Alaska, and you were getting hammered with snow and cold because the see-saw, basically -- because cyclones have to have return air, Earth will always have some sort of asymmetry in it. So in the -- in the simplest way, without getting into the deep details, no one should expect that it’s all warming. If that were the case, we would be in really big trouble. Earth doesn’t work that way. There will be centers of warming and centers of cooling even in the -- in the most extreme warming or cooling conditions. So there were probably relatively nice places during the Ice Ages, as a consequence, as well. So does that sort of help explain it? And yeah. It’s -- you know, the Vikings knew about that, you know. They just knew. Yeah. If it’s a good here, it’s bad there. Eastern Canada ’s had cold -- cold winters for a long time while we’ve been suffering through warm winters. MEMBERS OF AUDIENCE: Suffering? Matthew: Well -- well, ask yourself -- this gets back to the human dimension. A human dimension of climate warming last year in Fairbanks is we set an all-time record for automobile accidents. Why? The roads were icy and slick. I don’t personally think that was a benefit of climate warming. True, your kids didn’t have to wear as much clothing, but I didn’t see any benefit to that. I mean, I thought that was -- in terms of a human impact decline in warming, because we hover around -- you know, because hovering around the freezing is a bad deal, I think, throughout Alaska, you ought to be either above freezing or below freezing, but not right around it. And that’s -- that’s bad, I think, in every village and town in the state. Whenever we get near freezing weather, it’s bad stuff. You know. MEMBER OF AUDIENCE : And this year we’ve had a lot of rain, not just right around freezing. Matthew: Yeah. MEMBER OF AUDIENCE : What effect, if any, do you know does a layer of rain and sleeting rain or snow, what does that effect -- Matthew: Well, there are two things I didn’t mention, but let me first talk about rain in general. If -- if you don’t know, let me tell you this: In order to change the state of water, it -- it takes a huge amount of energy. 600 times more than it takes to warm it. That’s called the latent heat of freezing or cooling. So if we inundate a system with liquid water, we’ll hold off its freezing for a long time because we’ve got to freeze up all that water. So the first thing is, is wet -- you know, what happens before winter matters. Wet, wet ground, saturated ground, bogs and swamps, all keep themselves a lot warmer because before they can freeze, they -- before they can cool, they have to freeze. Okay. So that’s the first thing. The second thing, then, as far as -- so that’s if it’s raining before the snow. If it sort of rains and turns into snow, most of those -- most of the problems that I’ve heard of that sort of impact problems come with grazers. One of the biggest problems is that if you get freezing rain on tundra, grazers, the ones that have to crater that can’t get to what they need to crater to. So freezing rain turning to snow mainly glues the tundra down for those things that want to graze on it. I’ve heard people’s -- Sverre Pedersen told me that the Teshepuk Herd moved in a year where we had a distinct freezing rain event on the North Slope early in the season. And we -- we were out that season, you dig a snow pit you get down and there was this kind of concrete-like snow glued to the tundra. It was only about this thick. It wasn’t very thick stuff, but there it was and you couldn’t -- we would have to use a trowel to get through it. And I know the caribou were having trouble. So there are other sort of more subtle things that I could go into, but probably less important. It does change a lot of some of the dynamics of the snowpack, but that’s the biggest one I know of, sort of freezing rains in addition to bad roads. So... MEMBER OF AUDIENCE : There was a teacher that came -- is originally from Ekuk and she’s teaching up at Barrow and she goes to -- she goes home every summer to go fish and pick some berries. Matthew: Uh-hum. MEMBER OF AUDIENCE : And what she said this year there were no berries. Matthew: What town was she from? MEMBER OF AUDIENCE : It’s near Dillingham, Ekuk. Matthew: Yeah. I didn’t -- I don’t know that part of Alaska very well. MEMBER OF AUDIENCE : And they are were wondering because it never snowed this past winter, or there was very little snow and there was no -- and I guess there was no insulation or something. There were no berries this year. Matthew: Well, I want to say -- I’m a physicist and -- but I’ve spent the last decade doing snow ecology; in other words, working with plant people. And I have to say up front that that’s -- as soon as you get into the living world, the interactions are very complicated. And I’ve learned not to jump to any conclusions. I have no idea. You’d have to know more about blueberry bushes and how they function before you could figure out why the blueberry crop, how it was tied to the snow. That it might be tied to the snow is certainly plausible, but the mechanisms -- the shrub people I work with, I’m -- I’m learning stuff all the time. I just learned, you know, that the microbes in the soil can be bacterial or fungal. I just learned that there’s a shift that takes place in the middle of the winter I didn’t know anything about. I’m leaving day after tomorrow to AGU, we’re holding a special session to talk about snow and microbes. So as soon as you bring the biological or the human, Bill would say this, you get really complicated. So I usually retreat back to physics and say screw it, it’s too complicated, I’m just going to do the numbers. You know. So I’m sure the snow could have had something to do with it, but how, you’d have to find a good botanist to say what do blueberries need. MEMBER OF AUDIENCE : Adding to this, over the years in the villages I’ve heard a lot of the ladies talk about that, talk about the berries, how winter is going to affect the berries. They seem to know because of their observation over time. Matthew: It would be great to sort of -- this is -- this is the challenge of traditional knowledge like that. And then you’ve got to get those ladies and -- and -- and try and figure out, the knowledge is real, what’s the connecting links. And -- and if you could do that with a class, it would be great because -- and it’s real, but it’s sort of what are the actual mechanisms and processes. You know. And they may know or they may not know. They may know the end result, you know, sort of like I may not know the state of the road, but I know I put on my brakes and I’m sliding. Well, I can guess that it was icy. MEMBER OF AUDIENCE : Do they know -- I mean, if they are using patterns like these and they are relating to berry crops. I mean, there could well -- Matthew: Oh, absolutely, yeah. MEMBER OF AUDIENCE : There are all kinds of correlations. Matthew: You’ve got to find the common language, and that’s the challenge, and that’s really the exciting challenge. And you’ve got to sort of proof the knowledge by, you know, does one of the ladies say one thing and the other says the same thing and the third says the same thing, and you finally figure out, wow, it must be whether we get a frost in the fall or how much snow. You know, then you’re really on -- then you’re starting to understand what the actual connective link is. If that’s what you want to do. If you just want to pick berries, you don’t need to know the connective link, you just need to know, I bet we’re going to not get berries this year. My wife and family, we pick berries below our house. It’s the same. We have bounder crop this year, had a miserable crop last year, and I don’t know why. Blueberries. I don’t know why. MEMBER OF AUDIENCE : The low bush cranberries were terrible this year. So -- Matthew: We didn’t pick those, so I didn’t -- yeah. So I haven’t a clue how the winter snow, but we had very low snow last year, you know, and we had great berries this summer. I don’t know if they are connected at all. Any other questions? Well, good luck with your -- MEMBER OF AUDIENCE : Thank you. Matthew: -- endeavors. Yeah.